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NlTE TATES ATENT FFIQE.

AUGUSTUS SCHULTZ, OF NEW YORK, N. Y.

TAWING HIDES AND SKINS.

SPECIFICATION forming part of Letters Patent No. 291,785, dated January 8, 1884,

Application filed July 18, 1883. (No specimens.)

To all whom it may concern:

Be it known that I, AUeUs'rUs SoHULTZ, a citizen of the United States, residing at New York, in the county and State of New York, have invented new and useful Improvements in Tawing Hides and Skins, of which the following is a specification.

This invention relates to a new process for treating hides or skins, said process consisting in subjecting said hides or skins to the action of a bath prepared from a metallic saltsuch as bichroma-te of potash-and of then treating the same with a bath containing sulphurous acid.

In carrying out my process I unhair the raw hides and prepare them in the same manner in which they are made ready for tanning. If the hides have not been pickled, I subject them to the action of a bath of bichromate of potash in an acid, such as hydrochloric acid 5 or, if the hides have been pickled, they may be treated in a solution of biohromate of potash in water without the addition of an acid. In this solution the hides are left for a longer or shorter time, according to their thickness and to the strength of the solution employed. A skiver or the face of a sheepskin can be done in a strong solution, as above described, in about fifteen minutes, while a full skin roan would require in the same solution about one hour. I call the solution weak if it contains five per cent. or less of the weight of the skins of bichromate of potash, and I call the solution strong if it contains more than five per cent. of bichrom'ate of potash. The skins are done if small pieces cut from the thickest part thereof show that the solutions have entirely penetrated. The skins are then ready to be taken out of the solution, and, after the adhering liquor has run off, the skins are introduced into the second bath, which consists, by preference, of sulphite of soda dissolved in water, to which an acid sueh as hydrochloric acidshould be added, in order to set free the sulphurous acid. The hydrochloric acid or its substitute may be added to the bath in a free state or through the medium of skins previously pickled, such skins being impregnated with the proper acid. The solution may be strong or weak of sulphite, and the quantity of acid used at first may be less than requisite to exhaust the bath of the sulphite, and more acid may be added if the skins show that more is required, which is indicated by the color of the skins. \Vhon the skins are done, they show a whitish, bluish, or greenish color, according to the time they are kept in the sulphite bath. A skiver which first has been exposed to the action of the bichromate bath for fifteen minutes will be ready by re maining in the sulphite bath about twenty minutes. For thicker skins a proportionately longer time is required.

For some skinssuch as calf or steer skinsit is desirable that the same, after having been Withdrawn from the second or sulphite loath, shall be returned to the bichromatebath, which imparts to them a brownish color and leaves them in a favorable condition to be colored black. The leather coming from the sulphite bath is especially adapted for light and also for dark colors, and by proper dyeing methods better and brighter colors can be produced than on leather done by tannin. After the leather is done in the manner above de-' scribed, it may be colored, soaped, and greased in the usual way.

Leather can also be made by reversing the operation and first soaking the hides in a sulphite bath, and then exposing them to the action of the bichromate bath. By using the baths described at a heat of about 80 Fahr enheit the process will be done in a shorter time than if the baths are used cold. Tawed leather made by myprocess is very strong, soft, and elastic, and my process is applicable to hides or skins of every description.

Instead of using sulphite of soda, I can use other sulphites or bisulphites in presence of an acid or an aqueous solution of sulphurous acid.

\Vhat I claim as new, and desire to secure by Letters Patent, is

The withiadescribed process for tawing hides and skins, said process consisting in subjecting the hides or skins to the action of a bath prepared from a metallic salt-such as bichrornate of potash-and then to the action of abath capable of evolving sulphurous acidsuch as a solution of sulphite of soda-4n pres ence of another acid-such as hydrochloric acidsubstantially as described.

In testimony whereof I have hereunto set my hand and seal in the presence of two subscribing witnesses.

AUGUSTUS SCHULTZ.

\Vitnesses:

W. Hwrr, E. F. .lhsrnnnusen. 

